1. Field of the Invention
The present invention relates to a toner used for electrophotography, electrostatic recording, magnetic recording and the like.
2. Description of the Related Art
In recent years, a higher energy saving effect and a longer life-span than before have been required for an electrophotographic apparatus. The units for achieving energy saving may include energy saving of the mechanical driving part of an electrophotographic apparatus and energy saving of an information processor. Especially, energy saving of a heat fixing apparatus is an effective unit. Specific units may include a reduction in the size of the members in the heat fixing apparatus and an improvement in heating efficiency, and a particularly effective unit is a reduction in the temperature during heat fixing.
In order to achieve the heat fixing at lower temperatures than before, toner particles tend to have a structure that is more easily softened by heat and is easily melted. However, when the softened toner particles are mechanically loaded, an external additive is easily embedded therein, and the longer life-span cannot be easily achieved. Consequently, many proposals of external additives having a large particle size that cannot be easily embedded in the toner surface have been made at present.
Japanese Patent Application Laid-Open Nos. 2002-318467 and 2007-279702 have proposed the use of silica particles as an external additive having a large particle size. Japanese Patent Application Laid-Open No. 2005-202131 and WO 2013/063291 have proposed the use of organic-inorganic composite fine particles as an external additive having a large particle size. However, these external additives do not show the effect of improvement of adhesion and accumulation of molten toner to a fixing unit member due to hot offset and occurrence of an image failure by the adhesion and accumulation thereof. The contamination of the fixing unit member by the molten toner that is hot offset is increasingly becoming a serious problem with the longer life-span of the electrophotographic apparatus, and a solution of the problem has been sought.